The United States is ready to back NATO membership for Montenegro, provided the former Yugoslav republic continues to pursue reforms and increases popular support for joining the Western security alliance, the White House said.

Vice President Joe Biden told Montenegrin Prime Minister Milo Djukanovic in a telephone call on September 14 that the United States would support extending a NATO membership invitation to Montenegro at the group's foreign ministers meeting in December, so long as it continues to make progress in those areas.

"The vice president and prime minister agreed that Montenegro's membership in NATO would firmly anchor Montenegro in Euro-Atlantic institutions, promote greater regional stability in the Balkans, and demonstrate the credibility of NATO's Open Door policy," the White House said.

Montenegro, with 620,000 residents, wants to follow in the footsteps of neighboring Albania and Croatia, which joined NATO in 2009.

Allowing NATO membership for the former communist nation could escalate tensions between Russia and the Western alliance. Russian officials have said the entry of such nations could be seen as a provocation.